Use the Arrow keys with SHIFT button hold down to turn
the vector field. Use the Arrow keys without SHIFT button
to turn the weel.
CURL (type the key C to switch to curl):
The paddle wheel turns in the counter clockwise if the curl of the
vector field is positive at that point and clockwise , if the curl of
the vector field is negative.
DIV (thpe the key D to swtich to div):
The oxtahedron expands if the divergence of the vector field
is positive at that point, otherwise, it contracts.
